XCOM: Enemy Unknown is a reimagining of the 1994 PC classic UFO: Enemy Unknown, which is widely regarded as one of the best turn-based strategy games of all time. However, as this year's Syndicate reboot proved, remaking a revered classic is never an easy task, especially when the temptation is there to tinker with a winning formula. Fortunately, Firaxis has remained true to the series' roots, bringing XCOM up to date without losing what it is that made the original such a memorable release.

The story is a classic tale of alien invasion and human resistance. With an extraterrestrial threat landing on Earth, destroying cities and wiping out civilians, it's up to the newly formed XCOM organization to restore order and reduce panic. Overseen at the XCOM command center, but taking place in various locations throughout the world, the rather silly story provides context for your actions, all the while increasing tension and providing mild scares.

The plot plays second fiddle to the gameplay, however, which is split into two distinct categories. On the one hand, XCOM is a turn-based strategy game, on the other, it's a deep management title in which players use resources to research alien technology, build new facilities and manage a team of soldiers. It's a fantastic combination of gameplay styles, proving equally compulsive whether on the battlefield or managing resources behind the scenes.

The battle missions take place on isometric maps packed with buildings, debris, landmarks and at times, civilians. Initially in charge of a squad of four, players take turns with the computer to move soldiers into position, fire on enemies and carry out optional objectives. Almost all objects on the map serve a strategic purpose, whether it's the cover that only a wrecked car can provide, or the improved vantage point of an abandoned rooftop.

Battles are a statistical affair, though the game never bogs players down with too many numbers or complex rules. Instead, successful offense and defense is the result of a balanced squad, carefully positioned troops and sufficient technological research. As the game progresses, surviving battles becomes incredibly difficult, especially when tougher enemies are introduced with new skills and weapons. The game never feels unfair, however, and a failed mission is usually the result of a botched move, or a lack of investment in the right kind of research.

The great thing about XCOM is that failure to defeat your enemy has very real consequences, especially for your squad. A fallen comrade doesn't simply reappear when players restart the mission; instead, they're gone forever. Not only is this heartbreaking for those who have customised their soldiers and used them since day one, but it's also mightily inconvenient if they're highly ranked and skilled. It just goes to show that players can become emotionally invested with characters without having to sit through hours of cutscenes.

Of course, success on the battlefield is heavily influenced by what goes on at XCOM HQ. After deciding where to set up camp, players have access to numerous facilities, such as a research center, barracks and an engineering department. With one eye on the budget and another on resources earned in battle, including alien corpses and raw materials, players must use the various departments to unlock new weapons, items, missions and information.

Failure to invest in the right kinds of equipment, however, will leave users short on the battlefield, which inevitably leads to fallen soldiers and failed missions. Again, much like the combat, the strategy side of XCOM: Enemy Unknown isn't unnecessarily complicated, but it's deep enough to immerse players for many hours, and important enough that a few bad decisions will see users forced to start over. It reinforces the idea that every action has a consequence, which is unusual in an age where players can restart missions in an instant.

Even choosing a mission isn't straightforward. Different missions provide different rewards, such as extra scientists to speed up research, more money or an increased number of raw materials. But that's not all, as part of a league of nations, players have a responsibility to take care of each participating country. Ignore the needs of one region for too long and you risk widespread panic, and are likely to lose funding. Finding the balance between reward and duty is tough, although in the long term, it's better to have more financers for those bigger projects.

Multiplayer, meanwhile, sees two players battle it out on a rather limited selection of maps, using points to purchase squad members and skills. The experimental nature of the points system allows for some interesting squad combinations, as does the ability to fill teams with both humans and aliens. Turns are also timed, which increases the tension and requires a little extra skill. The points system and speed elements make the online mode feel unique, although randomly generated maps and the ability to save multiple teams would have almost certainly improved the experience.

The main campaign is also home to a few flaws, although most are superficial. Maps, for example, are recycled once too often, while the slightly bland, colourless visuals are far from spectacular. The camera also proves problematic, particularly when entering buildings, where it isn't always possible to pan around and visualize targets. Compared to a mouse and keyboard, directing units with an Xbox 360 controller can be a little fiddly, although it does work better than expected.

XCOM: Enemy Unknown is a wonderful game, which, despite being based on a near 20-year-old release, feels somehow fresh and stands apart from its rivals. It's deep, engaging, intuitive and inclusive, and is likely to invade consoles and PCs for quite some time.